A Compound that Modulates Lipoteichoic Acid Prevents Cariogenic Biofilm Accumulation

Objectives: Dental caries is a diet-biofilm-dependent public health problem. Streptococcus mutans contributes to biofilms that caused caries via production of an extracellular matrix rich in exopolysaccharides and acids. This study aimed to determine the effect of topical treatments with compound 1771 (an agent that modulates lipoteichoic acid metabolism) and myricetin (a flavonoid that affects the synthesis of S. mutans exopolysaccharides) on S. mutans in vitro biofilms.
Methods: First, the minimal inhibitory concentration (MIC) for compound 1771 and myricetin was evaluated. Next, 2xMIC of both agents alone and combined with and without fluoride were used for topical treatments. In vitro S. mutans UA159 biofilms were grown on saliva-coated hydroxyapatite discs, using tryptone-yeast extract broth with 25% whole saliva and alternating 0.1% sucrose and 0.5% sucrose plus 1% starch (37^oC, 5% CO₂). Twice-daily topical treatments were performed with: compound 1771 (2.6 µg/mL), myricetin (500 µg/mL), compound 1771+myricetin, fluoride (250 ppm), compound 1771+fluoride, myricetin+fluoride, compound 1771+myricetin+fluoride, and vehicle (3.2% ethanol plus 0.02% DMSO). After 67 hours, biofilms were evaluated to determine biofilm biomass, S. mutans viable counts, and water-soluble and -insoluble exopolysaccharides in the matrix. The pH of the spent media was measured.
Results: The compound 1771 alone lead to biofilms with lower S. mutans counts, biomass, and both types of exopolysaccharides (p≤0.05; vs. vehicle). However, the combination of compound 1771+myricetin+fluoride was able to decrease 3 logs of S. mutans counts, 60% of biomass, 74% and 85% of water-soluble and -insoluble exopolysaccharides in the matrix, respectively (vs. vehicle). The agents combined with fluoride lead to higher pH values in the spent media (vs. vehicle or agents alone or combined).
Conclusions: Therefore, the topical application of a compound that modulates lipoteichoic acid metabolism prevented the accumulation of S. mutans biofilm in vitro. Moreover, the effect was more pronounced when compound 1771 was associated with fluoride and a flavonoid.